Coupling Effects of Population Regulation Technologies on High Quality and Low Tar Tobacco in Nanping, Fujian

It is of great significance to study population regulation technologies for high quality and low tar tobacco raw materials in Nanping, Fujian, which is one of the most potential high quality and low tar content tobacco planting regions in China. To explore the coupling effect of population regulation technologies of high quality and low tar tobacco in Nanping, a 312-D optimized saturation design experiment with three factors of nitrogen application amount, plant spacing and number of leaves left was carried out in 2018—2019, and its influence on the comprehensive score index based on tar content, sensory quality and unit output value was studied, and the management scheme of population regulation techniques for high quality and low tar tobacco was optimized. The results showed that the main effects of single factor affecting the comprehensive score at the experimental levels were plant spacing>nitrogen application amount≈number of leaves left, and the marginal effects were reverse, and the coupling effects of the two factors promoted each other. Among the combined optimization schemes with different comprehensive score objectives, the coupling effect of medium fertilizer and medium population was the best. The optimal management scheme with comprehensive score exceeding 0.8 was nitrogen application amount of 6.188-10.089 kg/666.7 m², plant spacing of 0.398-0.626 m, and the number of leaves left of 15.460-19.749 pieces. Of which the maximum acceptable tar reduction effect optimization scheme was nitrogen application rate of 8.976 kg/666.7 m², the plant spacing of 0.437 m, and the number of leaves left of 17.229 pieces.